Antibiotic therapy for small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth is an under-recognised diagnosis with important clinical implications when untreated.

However, the optimal treatment regimen remains unclear.

Dr Sewell and colleagues from California, USA performed a systematic review and meta-analysis comparing the clinical effectiveness of antibiotic therapies in the treatment of symptomatic patients with documented small intestinal bacterial overgrowth.

The team searched 4 databases to identify clinical trials comparing effectiveness of different antibiotics, different doses of the same antibiotic, and antibiotics compared with placebo.

Data were independently extracted according to predetermined inclusion and exclusion criteria.

Rifaximin was the most commonly studied antibiotic with overall breath test normalization rate of 50%

Alimentary Pharmacology & Therapeutics

Study quality was independently assessed.

The researchers' primary outcome was normalization of post-treatment breath testing.

The secondary outcome was post-treatment clinical response.

Of 1356 articles identified, 10 met inclusion criteria.

The research team found that rifaximin was the most commonly studied antibiotic with overall breath test normalization rate of 50%.

The team observed that antibiotic efficacy varied by antibiotic regimen and dose.

Antibiotics were more effective than placebo, with a combined breath test normalization rate of 51% for antibiotics compared with 10% for placebo.

Meta-analysis of 4 studies favored antibiotics over placebo for breath test normalization with an odds ratio of 2.55.

The team heterogeneously evaluated clinical response among 6 studies, but tended to correlate with breath test normalization.

Dr Sewell's team concluded, "Antibiotics appear to be more effective than placebo for breath test normalization in patients with symptoms attributable to small intestinal bacterial overgrowth, and breath test normalisation may correlate with clinical response."

"Studies were limited by modest quality, small sample size and heterogeneous design."